Maciaszek Marek, Žalandauskas Vytautas, Silkinis Rokas, Alkauskas Audrius, Razinkovas Lukas
Center for Physical Sciences and Technology (FTMC), Vilnius LT-10257, Lithuania.
Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, Poland.
J Chem Phys. 2023 Aug 28;159(8). doi: 10.1063/5.0154319.
Detailed characterization of deep-level color centers requires understanding their electronic and atomic structure, which is most commonly investigated utilizing the Kohn-Sham density functional theory. Standard semilocal functionals based on the generalized gradient approximation (GGA) are inclined toward an imprecise quantitative description of defects' electronic structure. Hybrid functionals provide an improved prediction of electronic properties, albeit at a much higher computational cost. In this work, we test the newly developed Strongly Constrained and Appropriately Normed (SCAN) family of meta-GGA density functionals for selected color centers in diamond. In particular, we study nitrogen-, silicon-, germanium-, and tin-vacancy centers that have been recently investigated for their use in quantum technological applications. We show that SCAN and its derivatives, the rSCAN and r2SCAN functionals, significantly improve the calculated energies of optical transitions within the delta-self-consistent-field approach, almost reaching the accuracy of the hybrid Heyd-Scuseria-Ernzerhof (HSE) functional. In the case of the NV- center, we also show that the SCAN family of functionals improves the description of the adiabatic potential energy surfaces compared to both GGA and hybrid functionals, improving calculated luminescence lineshapes. As a result of these findings, we recommend using the SCAN family of functionals as a promising alternative for studying color centers in solids.
对深层色心进行详细表征需要了解其电子和原子结构，这通常利用Kohn-Sham密度泛函理论进行研究。基于广义梯度近似（GGA）的标准半局域泛函倾向于对缺陷的电子结构进行不精确的定量描述。杂化泛函虽能改进对电子性质的预测，但其计算成本要高得多。在这项工作中，我们针对金刚石中选定的色心测试了新开发的强约束且适当归一化（SCAN）系列元GGA密度泛函。特别是，我们研究了最近因其在量子技术应用中的用途而被研究的氮、硅、锗和锡空位中心。我们表明，SCAN及其导数rSCAN和r2SCAN泛函在δ自洽场方法中显著提高了光学跃迁的计算能量，几乎达到了杂化Heyd-Scuseria-Ernzerhof（HSE）泛函的精度。在NV-中心的情况下，我们还表明，与GGA和杂化泛函相比，SCAN系列泛函改进了绝热势能面的描述，改善了计算的发光线形。基于这些发现，我们建议将SCAN系列泛函作为研究固体中色心的一种有前景的替代方法。
